The invention relates to an air intake system for cooling air, which is fed to at least one heat exchanger and/or cooling surfaces of assemblies of a self-propelled harvesting machine. The inventive air intake system comprises a sieve through which the cooling air flows and which is equipped, on the inlet side, with a device for removing and shredding components of the cooling air adhering to the inlet-side surface of the sieve. The device comprises a suction device and a cutting device. The cutting device is formed of comb-like elements on the surface of the sieve and on a surface section of the suction device facing the surface of the sieve, or is formed of a front element connected to the surface section of the suction device.
Self-propelled harvesting machines according to the aforementioned type can be designed as forage harvesters or as combine harvesters. In the case of a self-propelled forage harvester, a stalked crop or corn is picked up via a front attachment, is then fed to a preparation device comprising compression rollers, a chopping assembly and post-chopping devices and, finally is fed via a discharge accelerator and a swivellable upper discharge chute to a collecting vehicle. An adjustable flap disposed at the end of the upper discharge chute and the mobility of the upper discharge chute are used to direct the crop emerging therefrom such that this crop reaches the collecting vehicle and such that this collecting vehicle can be completely filled.
In the case of a self-propelled combine harvester, the crop also is picked up via a front harvesting attachment from which this crop is fed via a feed rake to a preparation device designed as a threshing mechanism and separating devices. Harvested wheat, rapeseed or corn kernels proceed from this preparation device into a grain tank, while the straw, corn stalks, and other components not intended to be harvested are deposited on the field. In order to harvest corn, the front harvesting attachment designed as a wheat and rapeseed header is replaced by a front harvesting attachment designed as a corn picker.
The aforementioned self-propelled harvesting machines are driven by an internal combustion engine, which is preferably disposed in the rear region thereof and is enclosed by covering parts. Typically, this is a water-cooled internal combustion engine comprising a heat exchanger designed as a radiator, through which coolant from a cooling circuit of the internal combustion engine and air surrounding the harvesting machine flow. In addition, oil coolers for a hydraulic system of the harvesting machine, charge air coolers, further assemblies, etc., can be disposed within this covering of the self-propelled harvesting machine. Moreover, air previously cleaned via an air filter and drawn in via an exhaust gas turbocharger for the combustion process of the internal combustion engine also can be drawn in within this region covered by covering parts. A sufficient quantity of air must always be available, of course, for the cooling of the related heat exchanger and for the combustion process.
During a harvesting process, however, the air surrounding the harvesting machine is highly contaminated. In the case of a wheat or rapeseed harvest, these contaminants comprise a large portion of dust, portions of short straw, etc. If the self-propelled combine harvester is used to harvest corn, the contaminants in the air can also be, in part, husk leaves that enclose the harvested corn cobs. In the case of self propelled forage harvesters, air contaminants occur that are formed of straw components of the chopped crop and, provided the self-propelled forage harvester is used to harvest corn for silage. These air contaminants also can be complete husk leaves or the components thereof.
Since, as previously explained, the internal combustion engine is disposed in the rear region of the harvesting machine, in the case of a self-propelled combine harvester, the air contaminants occurring in the region of the sieves and a combine-mounted straw chopper can greatly contaminate the air drawn in by the cooling system of the internal combustion engine and by other cooling assemblies. In the case of self-propelled forage harvesters, the air drawn in by the cooling-air blower in the rear region may comprise components of the chopped crop, since the outlet of the swivellable upper discharge chute is also located in this region.
For this reason, a sieve is disposed in the covering parts, which is designed as a wire grating or a perforated plate and filters out a substantial portion of contaminants contained in the air to prevent these contaminants from clogging the downstream lamella of the heat exchanger. The contaminants deposit on the sieve, however, and clog this sieve. Clogging the sieve thereby prevents an adequate amount of cooling air from being supplied to the particular heat exchanger disposed behind the sieve. The supplied quantity of cooling air also can be reduced after relatively short operating intervals in that large leaves, short straw, or other plant components accumulate on the inlet-side surface of the sieve and therefore block the inflow of cooling air. In the case of the corn harvest, the large leaves can be the husk leaves that enclose the corn cobs, which are difficult to remove from the surface of the sieve.
The sieve can be prevented from clogging by providing a suction device on the surface of the sieve on the inlet side, which continuously suctions up the foreign objects adhering to the inlet-side surface. Without such a suction device, it would be necessary for the driver of the self-propelled harvesting machine or a person responsible for the service of the harvesting machine to manually clean the sieve on a regular basis. This work is often not carried out, however, until the coolant temperature, hydraulic oil temperature or other temperatures rise and, therefore, excessively high component temperatures may cause damage to components of the internal combustion engine or the other assemblies. This can result in high costs and a relatively long standstill of the harvesting machine during the harvest.
An air intake system for cooling air of the type set is known from EP 0 566 981 B1. A sieve housing designed in the shape of a circle or pot and having radially extending spokes is disposed within this air intake system, wherein individual sieve fields extend between the spokes. Furthermore, the sieve housing has a central hub and is designed to be rotatable relative to a suction device designed as a radial arm. The purpose of this suction device is to generate a vacuum on the inlet-side surface of the individual sieve fields, which are guided past this sieve housing during rotation thereof to suction the foreign objects off of this surface. In addition, rakes equipped with tines are provided in the region of the spokes, which interact with a second rake. The second rake comprises crenellations and is formed at a leading edge of the suction device. During the cleaning process, the sieve housing is set into rotation by a belt drive, wherein the rakes equipped with tines pass through grooves between the crenellations of the second rake and thereby cut and shred pods, husks, leaves and other plant parts that are retained on the sieve.